That's why I had the (replace by magic numbers) in parenthesis. There may be some number where you can still attract legitimate sellers but is high enough so p

That's why I had the (replace by magic numbers) in parenthesis. There may be some number where you can still attract legitimate sellers but is high enough so people taking a risk to just peddle junk will turn a loss on average. The only way you get rid of the junk is to make their expected profit less than zero.